Solid phase synthesis of heterocycles by cyclization/cleavage methodologies

For the solid phase preparation of various (pharmacologically important) heterocycles, cyclization/cleavage (C/C) or cyclorelease strategies proved to be superior. CC approaches take utmost advantage of the benefits of solid phase synthesis. Besides the practical benefits of solid phase reactions, cyclative release approaches are distinguished especially because of the generally found high purity of the final detached products, since only the anticipated structures cleave off the resin. Also cyclization/cleavage strategies are "traceless", as the obtained moiety after cyclization is part of the formed heterocycle. Over the last thirty years numerous approaches towards important heterocycle classes have been published. Among the successfully applied strategies are carbon-nitrogen (sulfur) bond, carbon-oxygen bond, sulfur-sulfur bond and carbon-carbon forming reactions in the final cyclorelease step.